Not all computer radios can do all of the following mixes and there are many other mixes not covered  here.

Mixing refers to combining 2 servos to act together to get the effect you want.

Example:

Aileron/rudder mixing  for coordinated turns. (aileron servo mixed with the rudder servo)
Now when you input aileron control the rudder will follow without you touching the rudder stick.  This results in a smoother more efficient turn.

Flapperons-
Ailerons can be programmed to act as flaps for
landing control. The aircraft must be equipped with a servo on each aileron to use this feature.

Elevator/flaps Used mostly in aerobatics or racing to effect very fast turns or loops.

Example

When you pull elevator up the elevator goes up and the flaps go down causing a change in pitch AND an increase in lift in the wing. This is done at high speeds, or in planes that have very powerful motors.

Ailevator-

When you enable the ailevator mix, the
elevator halves will move with input from the ailerons causing the plane to roll much more quickly. This requires the two elevator servos to be controlled from separate channels on the radio. Typically this requires a 7 or 8 channel radio.

Snap Roll-

this is a mix that actually moves surfaces during a roll to create a highly coordinated and highly repeatable type of aerobatic maneuver. Ailerons and rudder will be controlled. Elevator is likely to be programmed in as well.

Camber Changing

A mix where the ailerons and flaps move together to change the shape of the wing while in flight by moving them slightly up or down, typically from a switch or dial.
Lowering the flaps and ailerons together creates a more under cambered wing increasing lift.

Airbrakes-